We have successfully implemented PayPal Payment Advance in TEST mode. Till yesterday, we were getting proper response http data from paypal after the order has been placed. However, today, after I enter test visa number and expire date/ year.. It shows following message instead of giving me back post data. "Thank you for your purchase, we are currently reviewing your order." Due to this, I am not able to work further. This is test sandbox account where i have setup PPA.
Got the answer... By mistake, i had update settings in paypal for "Payment Review" to Enable. I disabled it and got it working again. Hope this helps anyone in future to check this basic stuff first.